Hull Speed

Top reasons "Why...

1 -lying
2 -favorable waves. Hull speed is nothing more than a point on the speed/drag graph where the wave resistance rises rapidly. The waves a boat makes are rarely bigger than the waves the ocean is providing. My 10' kayak could make 200knt days -riding the right wave.
3 -favorable wind. Hull speed limit is due to righting and thrust limits. Downwind thrust is not limited by righting.

So, if you are not all hung up on going somewhere in a particular direction, or even in a straight line, the ocean will offer many days where a 40 ft boat can make 200knt days. The reason it is not common is that most are sailing to a destination, not to see how much water they can pass under their hull.

A good crew that sails a good boat all year in the trades will have a number of 200+ days/year -wind and waves simply aligned by chance.

 

Ha, Ha very good Skyak! GPS measurements used as evidence are often in error because of wind, current and wave effects. Here's something that I use, that can correct to a degree for those 3 effects: http://knotstick.com/index.htm

PC

 

Skyak try sailing a few Nm's - pottacruise - reread the facts theses speeds are on the log and GPS When a 43' cruising yacht displacing 21 tons has sailed this many 200 Nm days I'm only asking "why?"
There have been no comments about the prop 28"x17" four blade
It drives a 12v Alt makes 15 amps@5Kns and 35 amps@ 7Kns
The prop was 28x18.5 I had 3.5" of pitch taken off. We then sailed 3000 Nms- NZ to New Caledonia and back. This change generated so much drag the vessel would not sail over 8.5 kts. I then re-pitched to 17.5". Sailing NZ to CapeTown (15,000nm trip) the boat speed is back up to easily obtaining speeds of over 10kts.

 

SURFING - This is not going to sound good.
My wife while at the helm has seen 20+ knots on the log not the GPS in very large seas.
Our last passage South Georgia to Cape Town while on watch under autopilot with my feet up sitting in the pilothouse I watched the GPS climb steadily to 18.5 knots
In the past you don't always get to see the log or GPS but you differently know from the sound coming from the prop that the vessel is surfing.
The snapshots taken are real and only to show that 200 Nm days do happen
I'm not claiming Windora has ever sailed a 250 Nm Day.

 

Windora speed

I have been in many conversations where sailors talk about outlier hull speeds .They seem to be more prevalent as the rum bottle empties. In the case of Windora, it is hard to believe her speed in a very fresh breeze. My scientific take on the boat is that when Athol Burns drew her, all the stars were lined up!!If you sail enough there will hopefully come a day when you feel the force of a great designer on his best day. Ever a sceptic, I am pretty sure I took the picture of the gps posting 11 knots in conditions Phil describes and several more as Windora danced down the west coast of New Zealand. Boat designs have their mysteries but Burns' Windora perfectly describes his genius and BTW in an incredibly comfortable ride!!

 

having done 4 consecutive near-200-runs myself (& met lots&lots of cruisers on our 3 rtw's & talked with them about their passagetimes)I am of the firm opinion that such a hullshape will be incapable of it. Ours were from cococ/costa rica to the marquesas, good current with us, mature trades & tradewind-swells, boat going down them at up to 16kn & conditions like inside a washing mashine (34' open bridgedeck cat).
the pic of the gps-readout seems to prove me right: he would have photographed the very highest reading, & this would have to have been more than 11kn in the surfs!

"18,5KN?? - hes's just bs-ing us!

 

I have been looking over Phil's shoulder as this conversation continues and had a few chuckles. It never fails to amaze us how Windora clocks up the miles so I can imagine how difficult it must be for others to believe the figures. Nevertheless they are true. Not only fast but comfortable along with it. There is hardly a day goes by that we don't say how lucky we are to have such a fine boat. Hopefully we will get to share an anchorage with you someday and share a few tales over a rum or two. I wish Athol Burns was still alive so we could have a chat but unfortunately he passed away not long after we bought Windora....Lynda Christieson